An example wireless personal area network is a piconet, which is a wireless data communications system that allows a number of independent data devices to communicate with each other. A piconet is distinguished from other types of data networks in that communications are normally confined to a person or object that typically covers about 10 meters in all directions, and envelops the person or object whether stationary or in motion.
Ultra wide band radio technology departs from conventional narrow band radio and spread-spectrum technologies in that the bandwidth of the signal at −10 db is typically greater than 20% of the center frequency. Instead of transmitting a continuous carrier wave modulated with information or with information combined with a spread code, which determines the bandwidth of the signal, a UWB radio transmits a series of very narrow impulses. For example, these impulses can take the form of a single cycle or monocycle, and have pulse widths less than 1 ns. These short time-domain impulses transformed into the frequency domain result in the ultra wide band spectrum of UWB radio technology.
In UWB radio technology, the information conveyed on the signal can be coded by pulse position modulation (PPM). In other words, information coding is performed by altering the timing of the individual pulses. More precisely, the series of impulses is transmitted at a repetition rate of up to several megahertz. Each pulse is transmitted within a window having a predetermined length (pulse repetition period), for example 50 ns. With respect to a nominal position, the pulse is in an early position or in a late position, which permits encoding of a 0 or a 1. It is also possible to encode more than two values by using more than two positions shifted with respect to the nominal position. It is also possible to superimpose a modulation of the BPSK type on this position modulation. More generally, any modulation can be used.
The IEEE 802.15.3 MAC standard defines the wireless medium access control specifications for high rate wireless personal area networks (WPAN) in narrow band radio technology. However, up to now, no document defines the specification of a wireless data communication system, for example, a wireless personal area network using UWB radio technology, and more particularly, the synchronizing of two independent data devices of such a network communicating with each other with one of the devices acting as a coordinator of the network.